[PATCH v8 1/2] bus: mhi: Add mhi_queue_is_full function

[PATCH v8 1/2] bus: mhi: Add mhi_queue_is_full function

[Loic Poulain]

This function can be used by client driver to determine whether it's
possible to queue new elements in a channel ring.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
---
 v1->v5: not part of the series
 v6: Add this commit, used for stopping TX queue
 v7: no change
 v8: remove static change (up to the compiler)

 drivers/bus/mhi/core/main.c | 11 +++++++++++
 include/linux/mhi.h         |  7 +++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index a588eac..bab38d2 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1173,6 +1173,17 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, enum dma_data_direction dir,
 }
 EXPORT_SYMBOL_GPL(mhi_queue_buf);
 
+bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir)
+{
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ?
+					mhi_dev->ul_chan : mhi_dev->dl_chan;
+	struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
+
+	return mhi_is_ring_full(mhi_cntrl, tre_ring);
+}
+EXPORT_SYMBOL_GPL(mhi_queue_is_full);
+
 int mhi_send_cmd(struct mhi_controller *mhi_cntrl,
 		 struct mhi_chan *mhi_chan,
 		 enum mhi_cmd_type cmd)
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 9d67e75..f72c3a4 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -745,4 +745,11 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, enum dma_data_direction dir,
 int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
 		  struct sk_buff *skb, size_t len, enum mhi_flags mflags);
 
+/**
+ * mhi_queue_is_full - Determine whether queueing new elements is possible
+ * @mhi_dev: Device associated with the channels
+ * @dir: DMA direction for the channel
+ */
+bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir);
+
 #endif /* _MHI_H_ */
-- 
2.7.4

[PATCH v8 2/2] net: Add mhi-net driver

[Loic Poulain]

This patch adds a new network driver implementing MHI transport for
network packets. Packets can be in any format, though QMAP (rmnet)
is the usual protocol (flow control + PDN mux).

It support two MHI devices, IP_HW0 which is, the path to the IPA
(IP accelerator) on qcom modem, And IP_SW0 which is the software
driven IP path (to modem CPU).

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
---
  v2: - rebase on net-next
      - remove useless skb_linearize
      - check error type on mhi_queue return
      - rate limited errors
      - Schedule RX refill only on 'low' buf level
      - SET_NETDEV_DEV in probe
      - reorder device remove sequence
  v3: - Stop channels on net_register error
      - Remove useles parentheses
      - Add driver .owner
  v4: - prevent potential cpu hog in rx-refill loop
      - Access mtu via READ_ONCE
  v5: - Fix access to u64 stats
  v6: - Stop TX queue earlier if queue is full
      - Preventing 'abnormal' NETDEV_TX_BUSY path
  v7: - Stop dl/ul cb operations on channel resetting
  v8: - remove premature comment about TX threading gain
      - check rx_queued to determine queuing limits
      - fix probe error path (unified goto usage)

 drivers/net/Kconfig   |   7 ++
 drivers/net/Makefile  |   1 +
 drivers/net/mhi_net.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 321 insertions(+)
 create mode 100644 drivers/net/mhi_net.c

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 1368d1d..11a6357 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -426,6 +426,13 @@ config VSOCKMON
 	  mostly intended for developers or support to debug vsock issues. If
 	  unsure, say N.
 
+config MHI_NET
+	tristate "MHI network driver"
+	depends on MHI_BUS
+	help
+	  This is the network driver for MHI.  It can be used with
+	  QCOM based WWAN modems (like SDX55).  Say Y or M.
+
 endif # NET_CORE
 
 config SUNGEM_PHY
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 94b6080..8312037 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o
 obj-$(CONFIG_NLMON) += nlmon.o
 obj-$(CONFIG_NET_VRF) += vrf.o
 obj-$(CONFIG_VSOCKMON) += vsockmon.o
+obj-$(CONFIG_MHI_NET) += mhi_net.o
 
 #
 # Networking Drivers
diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
new file mode 100644
index 0000000..4ba146d
--- /dev/null
+++ b/drivers/net/mhi_net.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* MHI Network driver - Network over MHI
+ *
+ * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
+ */
+
+#include <linux/if_arp.h>
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/u64_stats_sync.h>
+
+#define MIN_MTU		ETH_MIN_MTU
+#define MAX_MTU		0xffff
+#define DEFAULT_MTU	16384
+
+struct mhi_net_stats {
+	u64_stats_t rx_packets;
+	u64_stats_t rx_bytes;
+	u64_stats_t rx_errors;
+	u64_stats_t rx_dropped;
+	u64_stats_t tx_packets;
+	u64_stats_t tx_bytes;
+	u64_stats_t tx_errors;
+	u64_stats_t tx_dropped;
+	atomic_t rx_queued;
+	struct u64_stats_sync tx_syncp;
+	struct u64_stats_sync rx_syncp;
+};
+
+struct mhi_net_dev {
+	struct mhi_device *mdev;
+	struct net_device *ndev;
+	struct delayed_work rx_refill;
+	struct mhi_net_stats stats;
+	u32 rx_queue_sz;
+};
+
+static int mhi_ndo_open(struct net_device *ndev)
+{
+	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+
+	/* Feed the rx buffer pool */
+	schedule_delayed_work(&mhi_netdev->rx_refill, 0);
+
+	/* Carrier is established via out-of-band channel (e.g. qmi) */
+	netif_carrier_on(ndev);
+
+	netif_start_queue(ndev);
+
+	return 0;
+}
+
+static int mhi_ndo_stop(struct net_device *ndev)
+{
+	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+
+	netif_stop_queue(ndev);
+	netif_carrier_off(ndev);
+	cancel_delayed_work_sync(&mhi_netdev->rx_refill);
+
+	return 0;
+}
+
+static int mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
+{
+	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	struct mhi_device *mdev = mhi_netdev->mdev;
+	int err;
+
+	err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
+	if (unlikely(err)) {
+		net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
+				    ndev->name, err);
+
+		u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
+		u64_stats_inc(&mhi_netdev->stats.tx_dropped);
+		u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
+
+		/* drop the packet */
+		kfree_skb(skb);
+	}
+
+	if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
+		netif_stop_queue(ndev);
+
+	return NETDEV_TX_OK;
+}
+
+static void mhi_ndo_get_stats64(struct net_device *ndev,
+				struct rtnl_link_stats64 *stats)
+{
+	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	unsigned int start;
+
+	do {
+		start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.rx_syncp);
+		stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
+		stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
+		stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
+		stats->rx_dropped = u64_stats_read(&mhi_netdev->stats.rx_dropped);
+	} while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.rx_syncp, start));
+
+	do {
+		start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.tx_syncp);
+		stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
+		stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
+		stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
+		stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
+	} while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.tx_syncp, start));
+}
+
+static const struct net_device_ops mhi_netdev_ops = {
+	.ndo_open               = mhi_ndo_open,
+	.ndo_stop               = mhi_ndo_stop,
+	.ndo_start_xmit         = mhi_ndo_xmit,
+	.ndo_get_stats64	= mhi_ndo_get_stats64,
+};
+
+static void mhi_net_setup(struct net_device *ndev)
+{
+	ndev->header_ops = NULL;  /* No header */
+	ndev->type = ARPHRD_NONE; /* QMAP... */
+	ndev->hard_header_len = 0;
+	ndev->addr_len = 0;
+	ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
+	ndev->netdev_ops = &mhi_netdev_ops;
+	ndev->mtu = DEFAULT_MTU;
+	ndev->min_mtu = MIN_MTU;
+	ndev->max_mtu = MAX_MTU;
+	ndev->tx_queue_len = 1000;
+}
+
+static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
+				struct mhi_result *mhi_res)
+{
+	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
+	struct sk_buff *skb = mhi_res->buf_addr;
+	int remaining;
+
+	remaining = atomic_dec_return(&mhi_netdev->stats.rx_queued);
+
+	if (unlikely(mhi_res->transaction_status)) {
+		u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
+		u64_stats_inc(&mhi_netdev->stats.rx_errors);
+		u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
+
+		kfree_skb(skb);
+
+		/* MHI layer resetting the DL channel */
+		if (mhi_res->transaction_status == -ENOTCONN)
+			return;
+	} else {
+		u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
+		u64_stats_inc(&mhi_netdev->stats.rx_packets);
+		u64_stats_add(&mhi_netdev->stats.rx_bytes, mhi_res->bytes_xferd);
+		u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
+
+		skb->protocol = htons(ETH_P_MAP);
+		skb_put(skb, mhi_res->bytes_xferd);
+		netif_rx(skb);
+	}
+
+	/* Refill if RX buffers queue becomes low */
+	if (remaining <= mhi_netdev->rx_queue_sz / 2)
+		schedule_delayed_work(&mhi_netdev->rx_refill, 0);
+}
+
+static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
+				struct mhi_result *mhi_res)
+{
+	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
+	struct net_device *ndev = mhi_netdev->ndev;
+	struct sk_buff *skb = mhi_res->buf_addr;
+
+	/* Hardware has consumed the buffer, so free the skb (which is not
+	 * freed by the MHI stack) and perform accounting.
+	 */
+	consume_skb(skb);
+
+	u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
+	if (unlikely(mhi_res->transaction_status)) {
+		u64_stats_inc(&mhi_netdev->stats.tx_errors);
+
+		/* MHI layer resetting the UL channel */
+		if (mhi_res->transaction_status == -ENOTCONN)
+			return;
+	} else {
+		u64_stats_inc(&mhi_netdev->stats.tx_packets);
+		u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
+	}
+	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
+
+	if (netif_queue_stopped(ndev))
+		netif_wake_queue(ndev);
+}
+
+static void mhi_net_rx_refill_work(struct work_struct *work)
+{
+	struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
+						      rx_refill.work);
+	struct net_device *ndev = mhi_netdev->ndev;
+	struct mhi_device *mdev = mhi_netdev->mdev;
+	int size = READ_ONCE(ndev->mtu);
+	struct sk_buff *skb;
+	int err;
+
+	do {
+		skb = netdev_alloc_skb(ndev, size);
+		if (unlikely(!skb))
+			break;
+
+		err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
+		if (unlikely(err)) {
+			net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
+					    ndev->name, err);
+			kfree_skb(skb);
+			break;
+		}
+
+		/* Do not hog the CPU if rx buffers are completed faster than
+		 * queued (unlikely).
+		 */
+		cond_resched();
+	} while (atomic_inc_return(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz);
+
+	/* If we're still starved of rx buffers, reschedule later */
+	if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
+		schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
+}
+
+static int mhi_net_probe(struct mhi_device *mhi_dev,
+			 const struct mhi_device_id *id)
+{
+	const char *netname = (char *)id->driver_data;
+	struct mhi_net_dev *mhi_netdev;
+	struct net_device *ndev;
+	struct device *dev = &mhi_dev->dev;
+	int err;
+
+	ndev = alloc_netdev(sizeof(*mhi_netdev), netname, NET_NAME_PREDICTABLE,
+			    mhi_net_setup);
+	if (!ndev)
+		return -ENOMEM;
+
+	mhi_netdev = netdev_priv(ndev);
+	dev_set_drvdata(dev, mhi_netdev);
+	mhi_netdev->ndev = ndev;
+	mhi_netdev->mdev = mhi_dev;
+	SET_NETDEV_DEV(ndev, &mhi_dev->dev);
+
+	/* All MHI net channels have 128 ring elements (at least for now) */
+	mhi_netdev->rx_queue_sz = 128;
+
+	INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
+	u64_stats_init(&mhi_netdev->stats.rx_syncp);
+	u64_stats_init(&mhi_netdev->stats.tx_syncp);
+
+	/* Start MHI channels */
+	err = mhi_prepare_for_transfer(mhi_dev);
+	if (err)
+		goto out_prep_err;
+
+	err = register_netdev(ndev);
+	if (err)
+		goto out_register_err;
+
+	return 0;
+
+out_register_err:
+	mhi_unprepare_from_transfer(mhi_dev);
+out_prep_err:
+	free_netdev(ndev);
+	return err;
+}
+
+static void mhi_net_remove(struct mhi_device *mhi_dev)
+{
+	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
+
+	unregister_netdev(mhi_netdev->ndev);
+
+	mhi_unprepare_from_transfer(mhi_netdev->mdev);
+
+	free_netdev(mhi_netdev->ndev);
+}
+
+static const struct mhi_device_id mhi_net_id_table[] = {
+	{ .chan = "IP_HW0", .driver_data = (kernel_ulong_t)"mhi_hwip%d" },
+	{ .chan = "IP_SW0", .driver_data = (kernel_ulong_t)"mhi_swip%d" },
+	{}
+};
+MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
+
+static struct mhi_driver mhi_net_driver = {
+	.probe = mhi_net_probe,
+	.remove = mhi_net_remove,
+	.dl_xfer_cb = mhi_net_dl_callback,
+	.ul_xfer_cb = mhi_net_ul_callback,
+	.id_table = mhi_net_id_table,
+	.driver = {
+		.name = "mhi_net",
+		.owner = THIS_MODULE,
+	},
+};
+
+module_mhi_driver(mhi_net_driver);
+
+MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
+MODULE_DESCRIPTION("Network over MHI");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Re: [PATCH v8 2/2] net: Add mhi-net driver

[Manivannan Sadhasivam]

Hi Loic,

On Wed, Oct 28, 2020 at 05:34:58PM +0100, Loic Poulain wrote:
> This patch adds a new network driver implementing MHI transport for
> network packets. Packets can be in any format, though QMAP (rmnet)
> is the usual protocol (flow control + PDN mux).
> 
> It support two MHI devices, IP_HW0 which is, the path to the IPA
> (IP accelerator) on qcom modem, And IP_SW0 which is the software
> driven IP path (to modem CPU).
> 

This patch looks good to me. I just commented few nits inline. With those
addressed, you can have my:

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>   v2: - rebase on net-next
>       - remove useless skb_linearize
>       - check error type on mhi_queue return
>       - rate limited errors
>       - Schedule RX refill only on 'low' buf level
>       - SET_NETDEV_DEV in probe
>       - reorder device remove sequence
>   v3: - Stop channels on net_register error
>       - Remove useles parentheses
>       - Add driver .owner
>   v4: - prevent potential cpu hog in rx-refill loop
>       - Access mtu via READ_ONCE
>   v5: - Fix access to u64 stats
>   v6: - Stop TX queue earlier if queue is full
>       - Preventing 'abnormal' NETDEV_TX_BUSY path
>   v7: - Stop dl/ul cb operations on channel resetting
>   v8: - remove premature comment about TX threading gain
>       - check rx_queued to determine queuing limits
>       - fix probe error path (unified goto usage)
> 
>  drivers/net/Kconfig   |   7 ++
>  drivers/net/Makefile  |   1 +
>  drivers/net/mhi_net.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 321 insertions(+)
>  create mode 100644 drivers/net/mhi_net.c
> 
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 1368d1d..11a6357 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -426,6 +426,13 @@ config VSOCKMON
>  	  mostly intended for developers or support to debug vsock issues. If
>  	  unsure, say N.
>  
> +config MHI_NET
> +	tristate "MHI network driver"
> +	depends on MHI_BUS
> +	help
> +	  This is the network driver for MHI.  It can be used with

network driver for MHI bus.

> +	  QCOM based WWAN modems (like SDX55).  Say Y or M.
> +
>  endif # NET_CORE
>  
>  config SUNGEM_PHY
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 94b6080..8312037 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o
>  obj-$(CONFIG_NLMON) += nlmon.o
>  obj-$(CONFIG_NET_VRF) += vrf.o
>  obj-$(CONFIG_VSOCKMON) += vsockmon.o
> +obj-$(CONFIG_MHI_NET) += mhi_net.o
>  
>  #
>  # Networking Drivers
> diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
> new file mode 100644
> index 0000000..4ba146d
> --- /dev/null
> +++ b/drivers/net/mhi_net.c
> @@ -0,0 +1,313 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* MHI Network driver - Network over MHI

Network over MHI bus.

> + *
> + * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
> + */
> +
> +#include <linux/if_arp.h>
> +#include <linux/mhi.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/skbuff.h>
> +#include <linux/u64_stats_sync.h>
> +
> +#define MIN_MTU		ETH_MIN_MTU
> +#define MAX_MTU		0xffff
> +#define DEFAULT_MTU	16384

Please add a prefix to avoid namespace issues in future...

> +
> +struct mhi_net_stats {
> +	u64_stats_t rx_packets;
> +	u64_stats_t rx_bytes;
> +	u64_stats_t rx_errors;
> +	u64_stats_t rx_dropped;
> +	u64_stats_t tx_packets;
> +	u64_stats_t tx_bytes;
> +	u64_stats_t tx_errors;
> +	u64_stats_t tx_dropped;
> +	atomic_t rx_queued;
> +	struct u64_stats_sync tx_syncp;
> +	struct u64_stats_sync rx_syncp;
> +};
> +
> +struct mhi_net_dev {
> +	struct mhi_device *mdev;
> +	struct net_device *ndev;
> +	struct delayed_work rx_refill;
> +	struct mhi_net_stats stats;
> +	u32 rx_queue_sz;
> +};
> +

[...]

> +static void mhi_net_rx_refill_work(struct work_struct *work)
> +{
> +	struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
> +						      rx_refill.work);
> +	struct net_device *ndev = mhi_netdev->ndev;
> +	struct mhi_device *mdev = mhi_netdev->mdev;
> +	int size = READ_ONCE(ndev->mtu);
> +	struct sk_buff *skb;
> +	int err;
> +
> +	do {
> +		skb = netdev_alloc_skb(ndev, size);
> +		if (unlikely(!skb))
> +			break;
> +
> +		err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
> +		if (unlikely(err)) {
> +			net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
> +					    ndev->name, err);
> +			kfree_skb(skb);
> +			break;
> +		}
> +
> +		/* Do not hog the CPU if rx buffers are completed faster than
> +		 * queued (unlikely).

s/completed/consumed

> +		 */
> +		cond_resched();
> +	} while (atomic_inc_return(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz);
> +
> +	/* If we're still starved of rx buffers, reschedule later */
> +	if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
> +		schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
> +}
> +
> +static int mhi_net_probe(struct mhi_device *mhi_dev,
> +			 const struct mhi_device_id *id)
> +{
> +	const char *netname = (char *)id->driver_data;
> +	struct mhi_net_dev *mhi_netdev;
> +	struct net_device *ndev;
> +	struct device *dev = &mhi_dev->dev;
> +	int err;

Since this is a networking driver, please stick to reverse xmas tree order for
local variables.

Re: [PATCH v8 1/2] bus: mhi: Add mhi_queue_is_full function

[Manivannan Sadhasivam]

On Wed, Oct 28, 2020 at 05:34:57PM +0100, Loic Poulain wrote:
> This function can be used by client driver to determine whether it's
> possible to queue new elements in a channel ring.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  v1->v5: not part of the series
>  v6: Add this commit, used for stopping TX queue
>  v7: no change
>  v8: remove static change (up to the compiler)
> 
>  drivers/bus/mhi/core/main.c | 11 +++++++++++
>  include/linux/mhi.h         |  7 +++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index a588eac..bab38d2 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1173,6 +1173,17 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, enum dma_data_direction dir,
>  }
>  EXPORT_SYMBOL_GPL(mhi_queue_buf);
>  
> +bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir)
> +{
> +	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> +	struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ?
> +					mhi_dev->ul_chan : mhi_dev->dl_chan;
> +	struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
> +
> +	return mhi_is_ring_full(mhi_cntrl, tre_ring);
> +}
> +EXPORT_SYMBOL_GPL(mhi_queue_is_full);
> +
>  int mhi_send_cmd(struct mhi_controller *mhi_cntrl,
>  		 struct mhi_chan *mhi_chan,
>  		 enum mhi_cmd_type cmd)
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 9d67e75..f72c3a4 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -745,4 +745,11 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, enum dma_data_direction dir,
>  int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
>  		  struct sk_buff *skb, size_t len, enum mhi_flags mflags);
>  
> +/**
> + * mhi_queue_is_full - Determine whether queueing new elements is possible
> + * @mhi_dev: Device associated with the channels
> + * @dir: DMA direction for the channel
> + */
> +bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir);
> +
>  #endif /* _MHI_H_ */
> -- 
> 2.7.4
> 

Re: [PATCH v8 2/2] net: Add mhi-net driver

[Loic Poulain]

On Fri, 30 Oct 2020 at 09:14, Manivannan Sadhasivam
<manivannan.sadhasivam@linaro.org> wrote:
>
> Hi Loic,
>
> On Wed, Oct 28, 2020 at 05:34:58PM +0100, Loic Poulain wrote:
> > This patch adds a new network driver implementing MHI transport for
> > network packets. Packets can be in any format, though QMAP (rmnet)
> > is the usual protocol (flow control + PDN mux).
> >
> > It support two MHI devices, IP_HW0 which is, the path to the IPA
> > (IP accelerator) on qcom modem, And IP_SW0 which is the software
> > driven IP path (to modem CPU).
> >
>
> This patch looks good to me. I just commented few nits inline. With those
> addressed, you can have my:
>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>


Thanks for your review Mani, going to address that points in v9.

>
> Thanks,
> Mani
>
> > Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> > ---
> >   v2: - rebase on net-next
> >       - remove useless skb_linearize
> >       - check error type on mhi_queue return
> >       - rate limited errors
> >       - Schedule RX refill only on 'low' buf level
> >       - SET_NETDEV_DEV in probe
> >       - reorder device remove sequence
> >   v3: - Stop channels on net_register error
> >       - Remove useles parentheses
> >       - Add driver .owner
> >   v4: - prevent potential cpu hog in rx-refill loop
> >       - Access mtu via READ_ONCE
> >   v5: - Fix access to u64 stats
> >   v6: - Stop TX queue earlier if queue is full
> >       - Preventing 'abnormal' NETDEV_TX_BUSY path
> >   v7: - Stop dl/ul cb operations on channel resetting
> >   v8: - remove premature comment about TX threading gain
> >       - check rx_queued to determine queuing limits
> >       - fix probe error path (unified goto usage)
> >
> >  drivers/net/Kconfig   |   7 ++
> >  drivers/net/Makefile  |   1 +
> >  drivers/net/mhi_net.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 321 insertions(+)
> >  create mode 100644 drivers/net/mhi_net.c
> >
> > diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> > index 1368d1d..11a6357 100644
> > --- a/drivers/net/Kconfig
> > +++ b/drivers/net/Kconfig
> > @@ -426,6 +426,13 @@ config VSOCKMON
> >         mostly intended for developers or support to debug vsock issues. If
> >         unsure, say N.
> >
> > +config MHI_NET
> > +     tristate "MHI network driver"
> > +     depends on MHI_BUS
> > +     help
> > +       This is the network driver for MHI.  It can be used with
>
> network driver for MHI bus.
>
> > +       QCOM based WWAN modems (like SDX55).  Say Y or M.
> > +
> >  endif # NET_CORE
> >
> >  config SUNGEM_PHY
> > diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> > index 94b6080..8312037 100644
> > --- a/drivers/net/Makefile
> > +++ b/drivers/net/Makefile
> > @@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o
> >  obj-$(CONFIG_NLMON) += nlmon.o
> >  obj-$(CONFIG_NET_VRF) += vrf.o
> >  obj-$(CONFIG_VSOCKMON) += vsockmon.o
> > +obj-$(CONFIG_MHI_NET) += mhi_net.o
> >
> >  #
> >  # Networking Drivers
> > diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
> > new file mode 100644
> > index 0000000..4ba146d
> > --- /dev/null
> > +++ b/drivers/net/mhi_net.c
> > @@ -0,0 +1,313 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/* MHI Network driver - Network over MHI
>
> Network over MHI bus.
>
> > + *
> > + * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
> > + */
> > +
> > +#include <linux/if_arp.h>
> > +#include <linux/mhi.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/netdevice.h>
> > +#include <linux/skbuff.h>
> > +#include <linux/u64_stats_sync.h>
> > +
> > +#define MIN_MTU              ETH_MIN_MTU
> > +#define MAX_MTU              0xffff
> > +#define DEFAULT_MTU  16384
>
> Please add a prefix to avoid namespace issues in future...
>
> > +
> > +struct mhi_net_stats {
> > +     u64_stats_t rx_packets;
> > +     u64_stats_t rx_bytes;
> > +     u64_stats_t rx_errors;
> > +     u64_stats_t rx_dropped;
> > +     u64_stats_t tx_packets;
> > +     u64_stats_t tx_bytes;
> > +     u64_stats_t tx_errors;
> > +     u64_stats_t tx_dropped;
> > +     atomic_t rx_queued;
> > +     struct u64_stats_sync tx_syncp;
> > +     struct u64_stats_sync rx_syncp;
> > +};
> > +
> > +struct mhi_net_dev {
> > +     struct mhi_device *mdev;
> > +     struct net_device *ndev;
> > +     struct delayed_work rx_refill;
> > +     struct mhi_net_stats stats;
> > +     u32 rx_queue_sz;
> > +};
> > +
>
> [...]
>
> > +static void mhi_net_rx_refill_work(struct work_struct *work)
> > +{
> > +     struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
> > +                                                   rx_refill.work);
> > +     struct net_device *ndev = mhi_netdev->ndev;
> > +     struct mhi_device *mdev = mhi_netdev->mdev;
> > +     int size = READ_ONCE(ndev->mtu);
> > +     struct sk_buff *skb;
> > +     int err;
> > +
> > +     do {
> > +             skb = netdev_alloc_skb(ndev, size);
> > +             if (unlikely(!skb))
> > +                     break;
> > +
> > +             err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
> > +             if (unlikely(err)) {
> > +                     net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
> > +                                         ndev->name, err);
> > +                     kfree_skb(skb);
> > +                     break;
> > +             }
> > +
> > +             /* Do not hog the CPU if rx buffers are completed faster than
> > +              * queued (unlikely).
>
> s/completed/consumed
>
> > +              */
> > +             cond_resched();
> > +     } while (atomic_inc_return(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz);
> > +
> > +     /* If we're still starved of rx buffers, reschedule later */
> > +     if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
> > +             schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
> > +}
> > +
> > +static int mhi_net_probe(struct mhi_device *mhi_dev,
> > +                      const struct mhi_device_id *id)
> > +{
> > +     const char *netname = (char *)id->driver_data;
> > +     struct mhi_net_dev *mhi_netdev;
> > +     struct net_device *ndev;
> > +     struct device *dev = &mhi_dev->dev;
> > +     int err;
>
> Since this is a networking driver, please stick to reverse xmas tree order for
> local variables.

Re: [PATCH v8 2/2] net: Add mhi-net driver

[Manivannan Sadhasivam]

On Wed, Oct 28, 2020 at 05:34:58PM +0100, Loic Poulain wrote:
> This patch adds a new network driver implementing MHI transport for
> network packets. Packets can be in any format, though QMAP (rmnet)
> is the usual protocol (flow control + PDN mux).
> 
> It support two MHI devices, IP_HW0 which is, the path to the IPA
> (IP accelerator) on qcom modem, And IP_SW0 which is the software
> driven IP path (to modem CPU).
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>   v2: - rebase on net-next
>       - remove useless skb_linearize
>       - check error type on mhi_queue return
>       - rate limited errors
>       - Schedule RX refill only on 'low' buf level
>       - SET_NETDEV_DEV in probe
>       - reorder device remove sequence
>   v3: - Stop channels on net_register error
>       - Remove useles parentheses
>       - Add driver .owner
>   v4: - prevent potential cpu hog in rx-refill loop
>       - Access mtu via READ_ONCE
>   v5: - Fix access to u64 stats
>   v6: - Stop TX queue earlier if queue is full
>       - Preventing 'abnormal' NETDEV_TX_BUSY path
>   v7: - Stop dl/ul cb operations on channel resetting
>   v8: - remove premature comment about TX threading gain
>       - check rx_queued to determine queuing limits
>       - fix probe error path (unified goto usage)
> 
>  drivers/net/Kconfig   |   7 ++
>  drivers/net/Makefile  |   1 +
>  drivers/net/mhi_net.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 321 insertions(+)
>  create mode 100644 drivers/net/mhi_net.c
> 

[...]

> +static int mhi_net_probe(struct mhi_device *mhi_dev,
> +			 const struct mhi_device_id *id)
> +{
> +	const char *netname = (char *)id->driver_data;
> +	struct mhi_net_dev *mhi_netdev;
> +	struct net_device *ndev;
> +	struct device *dev = &mhi_dev->dev;
> +	int err;
> +
> +	ndev = alloc_netdev(sizeof(*mhi_netdev), netname, NET_NAME_PREDICTABLE,
> +			    mhi_net_setup);
> +	if (!ndev)
> +		return -ENOMEM;
> +
> +	mhi_netdev = netdev_priv(ndev);
> +	dev_set_drvdata(dev, mhi_netdev);
> +	mhi_netdev->ndev = ndev;
> +	mhi_netdev->mdev = mhi_dev;
> +	SET_NETDEV_DEV(ndev, &mhi_dev->dev);
> +
> +	/* All MHI net channels have 128 ring elements (at least for now) */
> +	mhi_netdev->rx_queue_sz = 128;
> +
> +	INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
> +	u64_stats_init(&mhi_netdev->stats.rx_syncp);
> +	u64_stats_init(&mhi_netdev->stats.tx_syncp);
> +
> +	/* Start MHI channels */
> +	err = mhi_prepare_for_transfer(mhi_dev);
> +	if (err)
> +		goto out_prep_err;
> +
> +	err = register_netdev(ndev);
> +	if (err)
> +		goto out_register_err;
> +
> +	return 0;
> +
> +out_register_err:
> +	mhi_unprepare_from_transfer(mhi_dev);

Missed this one. MHI stack will do this for you incase of failure.

Thanks,
Mani